This invention relates generally to cutting apparatus and, in one or more aspects, a cutting apparatus that is particularly well suited for the cutting of wallpaper.
Cutting apparatus including adjustably extendable blades are known. One common example is a utility knife. A typical utility knife includes a housing with a blade opening in the front end thereof and a blade holder that linearly reciprocates within the housing for alternate extension and retraction of a cutting blade through the blade opening. Moreover, the blade holder of a utility knife is generally selectively lockable into various locking positions corresponding to different distances by which the blade extends from the housing. The linear movement of the blade holder is enabled by a linearly reciprocable button connected to the blade holder and accessible to a user from the exterior of the housing. Once the blade is locked into an extended position, manual intervention is typically required in order to move the blade back into the housing. Additionally, it is difficult, if at all possible, to alternately extend and retract the blade while the knife is being grasped for cutting; adjustment of one""s grasp is generally necessary in order to withdraw the blade into the blade housing.
One prior hand-held cutting tool described in U.S. Pat. No. 2,018,149 includes a holder with a blade carrier mounted for angular movement within the holder. An adjusting screw is connected to the blade carrier and cooperates with a thrust nut mounted on the screw. The angle of the blade carrier with respect to the holder is adjusted by turning the adjusting nut.
Various embodiments and versions of a cutting apparatus may include one or more of the following features.
In one embodiment, a cutting apparatus having a pivotable blade holder (hereinafter xe2x80x9ccutting apparatusxe2x80x9d) includes a blade housing having an internal blade cavity with a blade opening to the outside of the housing. The blade housing extends longitudinally between rear and forward ends and includes right and left sides and upper and lower surfaces. Pivotally mounted within the housing is a blade holder that is pivotable about a lateral axis passing through the left and right sides. The blade holder is pivotable between a fully retracted position in which the cutting edge of a cutting blade retained thereby is contained within the housing such that the cutting edge does not protrude through the blade opening to the outside of the housing and a second, cutting position in which the cutting edge of the blade at least partially protrudes through the blade opening to the outside of the housing.
Another version of a cutting apparatus having a pivotable blade holder includes a biasing member that normally biases the blade holder toward the fully retracted position and a blade actuator accessible from the outside of the housing, and cooperating with the blade holder, such that application of an external force by a user to the blade actuator moves the blade holder toward a cutting position in opposition to the biasing force of the biasing element. When the external force is removed from the blade actuator, the biasing element returns the blade holder toward the fully retracted position. The biasing member can be, for example, a torsion spring, leaf spring, coiled spring, elastic member or other resilient member. In one variation, the upper surface of the blade housing includes an actuator slot in communication with the blade cavity and the blade actuator depends from the blade holder and extends upwardly through the actuator slot where it is accessible to a user. The blade actuator includes an upper side that extends at least partially forward of the pivot axis such that a downwardly directed force (i.e., generally toward the lower surface of the blade housing) applied forward of the pivot axis to the upper side of the blade actuator urges the blade actuator toward a cutting position.
In another version, the lower surface of the blade housing defines a guide surface including at least a portion of the blade opening and along which the cutting apparatus is drawn over a material to be cut. The cutting position is such that the cutting edge of the blade inclines rearwardly with respect to the guiding surface so that, when the cutting apparatus is drawn rearwardly with the guiding surface in contact with the material to be cut, the cutting edge advances through the material at an acute angle.
In another embodiment, the maximum depth to which the blade can cut into a material is adjustable. More specifically, the maximum angle by which the blade holder can be pivotably displaced along an arc of an imaginary circle from the fully retracted position is adjustable. In one version, the cutting apparatus includes a depth adjuster that is selectively lockable into at least two locking positions, each of which locking positions corresponds to a different maximum angle by which the blade holder can be displaced with respect to the fully retracted position. In one variation, the housing includes an elongated track having fore and aft ends. The track extends longitudinally between the rear and forward ends of the housing along an imaginary chord of the imaginary circle. A depth adjuster is mounted for linear reciprocation between the aft and fore ends of the track. The depth adjuster includes a button accessible to a user from the exterior of the housing and a blade-holder bearing surface movable in tandem with the button and against which an arresting surface of the blade holder bears when the blade holder is maximally displaced from the fully retracted position. The depth adjuster is selectively lockable into at least two locking positions, each locking position corresponding to a different longitudinal position of the blade-holder-bearing surface. The blade-holder bearing surface is movable within the angular path of the blade holder such that a first locking position allows the blade holder to be displaced by a first maximum angle from its fully retracted position before the blade holder is arrested by the blade-holder bearing surface, and a second locking position allows the blade holder to be displaced by a second maximum angle before the blade holder is arrested by the blade-holder bearing surface. In one version, one locking position corresponds to a xe2x80x9csafetyxe2x80x9d position in which the blade holder cannot be pivoted to an extent that would cause the cutting edge of a blade retained thereby to protrude out of the housing. Alternatively, a separate locking member can be included, independent of the depth adjuster.
In another version of a cutting apparatus including a depth adjuster, the blade holder includes an arresting surface that extends forward of the pivot axis. The arresting surface is positioned and adapted for alternative contacting engagement and disengagement with the blade-holder bearing surface. Furthermore, the blade-holder bearing surface reciprocates along a linear path below the arresting surface and the arresting surface inclines rearwardly toward the pivot axis with respect to the reciprocation path of the blade-holder bearing surface such that more rearward positions of the blade-holder bearing surface correspond to greater maximum pivotal displacement angles of the blade holder than do more forward positions of the blade-holder bearing surface.
Although the scope and spirit of the invention are in no way limited by blade size or configuration, embodiments and versions adapted to house and retain standard rectangular razor blades are advantageous. Among the advantages of such embodiments are that standard rectangular razor blades are readily available and embodiments adapted to retain them can be compact.
In another version, the actuator slot extends longitudinally forward of the pivot axis in the upper surface of the blade housing, and is sufficiently elongated and wide, to enable the blade holder to pivot upwardly and protrude out of the blade housing into a position that enables removal and replacement of a cutting blade (i.e., a blade changing position). To prevent inadvertent pivoting of the of the blade holder into a blade changing position, one variation includes a blade-changing lock. The blade-changing lock includes a first lock element carried by the blade housing and a second lock element carried by the blade holder. The first and second lock elements are selectively moveable into locked and unlocked positions with one another. When the first and second lock elements are in a locked position, pivotal movement of the blade holder with respect to the blade housing is restricted between the fully retracted position and a cutting position. When the first and second lock elements are in an unlocked position, the blade holder can pivot upwardly into a blade changing position.
An advantage of a cutting apparatus including a housing and a pivotably mounted blade holder in which the maximum angular displacement is adjustable is that the cutting apparatus can be used to cut through materials of different thicknesses without cutting too deeply into a supporting surface under the material to be cut. This feature may prove particularly useful in the cutting and trimming of wallpaper, for example.
A version of a cutting apparatus having a pivotable blade holder and including a blade actuator in which downward depression thereof (i.e., generally toward a material to be cut) by a user""s finger causes the cutting edge of the blade to protrude from the housing is particularly well-suited for fine trimming work, such as the trimming of wallpaper. An advantage of such a cutting apparatus is that the force applied to extend the blade contributes to proper and natural grasping and control of the cutting apparatus while making cuts. As will be more fully appreciated upon examination of the detailed description and drawings, a user grasps such a version by applying opposed forces on either side of the blade housing with the thumb and side of the middle finger, while the index finger is positioned over the blade actuator. When a cut is to be made, the user depresses the blade actuator to extend the blade, places the cutting edge in contact with the material to be cut and pushes with the index finger into the material while drawing the cutting apparatus rearward. A further advantage is realized by including a biasing element that normally biases the blade holder toward the fully retracted position; once the user withdraws the blade from the material, he or she simply removes the force provided by his or her index finger and the blade withdraws into the housing.
Another advantage is provided by a version in which the blade holder can be pivoted into a blade changing position through the upper surface of the blade housing; unlike a utility knife, there is no need to disassemble the blade housing in order to change or reverse the blade.